Investments (Details) - USD ($)	3 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Mar. 31, 2019
Investments [Abstract]
Short-term investments	$ 3,100,000		$ 2,300,000
Available-for-sale debt securities	0		0
Sales of available-for-sale investments	$ 0	$ 1,376,600,000	1,380,000,000
Gross realized losses			$ 5,600,000